Brass is one of the most commonly used metals today. Brass is a deriveative of copper when
zinc is the primary alloying ingredient, besides copper.
Brasses may also have a small amount of other alloying elements in order to give it different advantageous properties.
Brass has excellent electrical conductivity and a high tensile strength. It rewards one with a brilliant shine when polished and there are as many types of brass as there are applications for it.
Brasses are suitable for fabrication via hot forging methods.The free machining grades set the bar for free machining, against which other metals are compared.
There are two classes of brass alloys:
- The alpha alloys - These are the brasses with less than 37 % zinc.
- The alpha/beta alloys These have between 37 - 45 % zinc.
The alpha alloys are ductile and therefore excellent for cold working. The alpha/beta or duplex alloys are limited in their cold ductility but are stronger and harder.
| Brass CZ121 Properties |
| Minimum Properties | Ultimate Tensile Strength, (MPa) | 410 |
| Proof Stress, | 0.2% (MPa) |
| Elongation A5(%) | 20 |
| Hardness | VPN |
| Chemistry | Copper (Cu) | 58% |
| Iron (Fe) | - |
| Manganese (Mn) | - |
| Nickel (Ni) | - |
| Lead (Pb) | 3% max |
| Zinc (Zn) | Balance |
| Physical Properties | Density | 8.47g cm3 |
| Melting Point | 875 deg |
| Modulus of Elasticity | 97 gpa |
| Electrical Resistivity | 0.062x10-6 ?.m |
| Thermal Conductivity | 123 W/m.K at 100°C |
| Thermal Expansion | 20.9 x10-6 /K at 100°C |
| Brass alloy CZ121corresponds to the following designations: |
| CEN | CW614N |
| BS | BS2874 |
| CZ121 |
| UNS | C38500 |
| ISO | CuZn39Pb3 |
This is a good machining grade as it falls into the CZ121 class. The added element of lead improves its machinability. The lead does not dissolve in the brass and the tiny particles act as chip breakers. Sometimes the letter "M" is added to the designation CZ121"M", this referrs to its good machining qualities.
- Corrosion resistance is fair to excellent
- Cold working is not recommended. This alloy can be knurled if need be.
- Hot working of CZ121 is excellent. This is best done between the temperature of 630 deg and 730 deg.
- Annealing or solution treatment can be carried out by quick cooling after heating to between 430 deg and 600 deg Celsius.
- Machinability is excellent. Its machinability rating is 90. As a comparison the Alloy 360 FC Brass is 100
- Welding - Brazing is rated as good and soldering as excellent. Welding is fair, however all other welding methods are not recommended.